Improvement in steam safety-yalyes



VIRGIL D. GREEN, OF WATERTOWNQ;WISCONSIN, ASSIGNOR T() HIMSELF AND E. M.HALL.- OF THESAME' PLACE.

Letters Patent No. 72,192, dated December 17, 1867.

IMPRVBMBNT 1N STEAM SAFETY-VALVES.

TO ALL WHOM IT MAY CONCERN:

Be it known that I, VIRGIL D. GREEN, of Watertown, in the county ofJeii`erson','and State of Wisconsin, have invented a new and usefulImprovement in AEquilibriutn- Balance for Safety-Valves; and I do herebydeclare` that the following is a full, clear, and exactdescriptionthereof, which will enable others skilled in the art to makeand use the saine, reference being had to the accompanying drawings,forming part of this specification.

'.Lhe object'ot' this invention is to overcome the rigidity ofthe springin the spring-balances in common use. It is well understood that, as thelever of the safety-valve is raisedgthe tension, and consequently therigidity, of the spring increases in proportion as the lever is raised;andthe invention consists in providing a cylinder which contains abarrel with a spiral spring within it, and withacam'and chain -attached,whereby I am enabled to overcome the diiliculties hitherto met with in'properly regulating the safety-valve, as will hereinafter be described.Y

And to enable others skilled in the art to make and use myinventiorn-Iwill proceed to describe its construction and operation.

Figure 1 represents a top view of my balance with the cap oil'.

Figure 2 is a central longitudinal section through the line :v :v offig. 1; and

Figure 3 is asection of the barrel through thevline y y, showing` thespiral spring and its fastenings. l,

Similar letters of reference indicate like parts. i

A represents the'eylinder; B, the barrel containing thespring. C isacentral shaft. D is aratehet-wheel on the shaft. E isthe safety-valvelever. F is the rod which connects the balance with the safety-valvelever. H is a chain, which connects the rod F to the barrel Br G is thespiral spring, attached to the shaft and tothe barrel, as seen in fig.3. The ratchet is attached to tbe sliziftand is held by a spring-peril,which is attached to the bottom of the cylinder A. It is seen in dottedlines in tig. 1, and represented by p.' Thespring is wound up in thebarrel by a key, which fits thertop'of the shaft, as seen in iig. 1.Upon theupper end of the barrel B there is a cam, m, to the side ofwhich the chain H is attached, the Aother end of thechain beingconnected to I the end of the rod Il',V after passing round the cam, asAseenin iig. 1.

It will be seen that the chain is attached to the cam at a point whichis farther frein the centre ofthe shaft than the point occupied bytheother end where itis connected to the rod F.

The balance being set, as represented in iig. 1, any addition to thestrain or rigidity of the spring serves to increase the leverage ordistance from the centre to the point ofV resistance, and, consequently,counteracts the increasing rigidity, by operating with a longer lever.In other words, the power to coil the spring, and which increases itsrigidity, is applied where the tangent loaves the cam, and the rod F isthe tangent.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is-'- The cylinder A, the drum B, the springG, the ratchet and pawl Dp, in combination withithe cam m and the chainH, substantially as described. f

VIRGIL D. GREEN.

Witnesses WALDo LYON, SAMUEL MeMULLIN.

